The invention relates to the catalytic homopolymerization and copolymerization of ethylene with high activity Mg and Ti containing complex catalysts in a low pressure gas phase process to produce polymers having a density of about .gtoreq.0.95 to .ltoreq.0.97, a melt flow ratio of about .gtoreq.22 to .ltoreq.32 and having a relatively round particle shape and a relatively low level of fines.